Ap Bio Evolution Practice Test

Ace Your AP Bio Evolution Exam: A Comprehensive Practice Test and Review

This comprehensive guide provides a robust AP Biology evolution practice test, designed to thoroughly assess your understanding of this crucial topic. Evolution is a cornerstone of AP Biology, encompassing a vast range of concepts from natural selection and genetic drift to speciation and phylogenetic analysis. This practice test will not only help you identify areas where you need further review but will also reinforce your understanding of key evolutionary principles. Mastering these principles is crucial for success on the AP Biology exam. This resource includes detailed explanations for each answer, providing a valuable learning opportunity beyond simple right-or-wrong feedback. Let's dive into the world of evolutionary biology!

Section 1: Multiple Choice Questions

Instructions: Choose the best answer for each multiple-choice question.

1. Which of the following is NOT a requirement for natural selection to occur? a) Variation in traits b) Inheritance of traits c) Overproduction of offspring d) Constant environmental conditions e) Differential reproductive success

2. The process by which unrelated organisms independently evolve similar traits due to similar environmental pressures is known as: a) Convergent evolution b) Divergent evolution c) Coevolution d) Parallel evolution e) Adaptive radiation

3. Genetic drift is most likely to significantly affect which of the following populations? a) A large, stable population b) A small, isolated population c) A population with high gene flow d) A population with a high mutation rate e) A population with high genetic diversity

4. Which type of selection favors individuals with extreme phenotypes? a) Stabilizing selection b) Directional selection c) Disruptive selection d) Artificial selection e) Sexual selection

5. The biological species concept defines a species as: a) A group of organisms that share similar morphological characteristics. b) A group of organisms that occupy the same ecological niche. c) A group of organisms that can interbreed and produce fertile offspring. d) A group of organisms that share a common ancestor. e) A group of organisms that are reproductively isolated from other groups.

6. Which of the following is an example of prezygotic reproductive isolation? a) Hybrid sterility b) Hybrid inviability c) Habitat isolation d) Reduced hybrid fertility e) Postzygotic isolation

7. The gradual accumulation of small changes over long periods leading to the formation of new species is known as: a) Punctuated equilibrium b) Gradualism c) Adaptive radiation d) Convergent evolution e) Allopatric speciation

8. Homologous structures are: a) Structures with similar function but different evolutionary origins. b) Structures with different function but similar evolutionary origins. c) Structures that have no apparent function. d) Structures that are only found in extinct species. e) Structures that are only found in closely related species.

9. Which of the following is a source of new genetic variation in a population? a) Genetic drift b) Natural selection c) Mutation d) Gene flow e) Both c and d

10. Which concept explains the observation that the fossil record shows many transitional forms between different groups of organisms? a) Punctuated equilibrium b) Gradualism c) Convergent evolution d) Divergent evolution e) Adaptive radiation

Section 2: Free Response Questions

Instructions: Answer the following free-response questions in complete sentences and provide detailed explanations.

Question 1: Describe the five conditions necessary for Hardy-Weinberg equilibrium. Explain what happens to allele and genotype frequencies when these conditions are not met. Give specific examples of how each condition can be violated in a real-world population.

Question 2: Compare and contrast allopatric and sympatric speciation. Provide specific examples of each type of speciation. Discuss the role of reproductive isolation in both processes.

Question 3: Explain the concept of natural selection. Describe three different types of natural selection (directional, stabilizing, and disruptive) with specific examples for each. Illustrate how each type of selection can affect the distribution of phenotypes in a population. Discuss the role of environmental factors in shaping the direction of natural selection.

Question 4: Describe the evidence supporting the theory of evolution. Include at least four different lines of evidence, such as fossil record, comparative anatomy, molecular biology, and biogeography. For each line of evidence, explain how it supports the idea of common descent and the process of evolutionary change.

Question 5: Discuss the role of genetic drift in evolution. Explain the difference between the bottleneck effect and the founder effect. Provide examples of how these effects can lead to significant changes in allele frequencies within a population. Explain why genetic drift is more pronounced in small populations.

Answer Key and Explanations

Section 1: Multiple Choice Questions

1. d) Constant environmental conditions: Natural selection thrives on environmental change; it is the driving force for adaptation.

2. a) Convergent evolution: This describes unrelated species evolving similar traits due to similar selective pressures.

3. b) A small, isolated population: In small populations, random fluctuations in allele frequencies are more impactful due to limited gene pool.

4. c) Disruptive selection: This favors individuals at both ends of the phenotypic spectrum, potentially leading to speciation.

5. c) A group of organisms that can interbreed and produce fertile offspring: This is the core definition of the biological species concept.

6. c) Habitat isolation: This prevents mating before fertilization can occur.

7. b) Gradualism: This refers to the slow, continuous change over time.

8. b) Structures with different function but similar evolutionary origins: For instance, the forelimbs of humans, bats, and whales.

9. e) Both c and d: Mutations introduce new alleles, and gene flow introduces new alleles from other populations.

10. b) Gradualism: The fossil record reveals a series of transitional forms that support gradual evolutionary change.

Section 2: Free Response Questions – Detailed Answers

Question 1: Hardy-Weinberg Equilibrium

The Hardy-Weinberg principle describes the conditions under which allele and genotype frequencies in a population remain constant from generation to generation. These five conditions are:

1. No mutations: Mutations introduce new alleles, altering allele frequencies. Example: A mutation in a gene responsible for pigmentation could lead to a new allele for coat color in a mammal population.

2. Random mating: Non-random mating, such as assortative mating (mating with similar individuals), alters genotype frequencies. Example: Plants with self-pollination exhibit non-random mating.

3. No gene flow: Gene flow (migration) introduces or removes alleles, changing allele frequencies. Example: Pollen from a different plant species drifting into a population can introduce new alleles.

4. No genetic drift: Genetic drift (random changes in allele frequencies due to chance events) is more pronounced in small populations. Example: A natural disaster decimating a population can drastically alter allele frequencies.

5. No natural selection: Natural selection favors certain alleles, changing their frequencies. Example: In a population of beetles, if green beetles are better camouflaged, their allele will increase in frequency.

When these conditions are not met, allele and genotype frequencies will change over time, resulting in evolution.

Question 2: Allopatric vs. Sympatric Speciation

Allopatric speciation occurs when populations are geographically separated, preventing gene flow. This isolation allows independent evolution, leading to reproductive isolation and ultimately, the formation of new species. Example: A population of squirrels separated by a river may eventually evolve into two distinct species.

Sympatric speciation occurs within the same geographic area. This can happen through various mechanisms, such as:

• Polyploidy: This involves changes in chromosome number (common in plants).
• Sexual selection: Different mating preferences or behaviors can lead to reproductive isolation. Example: Different mating calls in crickets.
• Habitat differentiation: Different groups within a population may specialize in different microhabitats. Example: Apple maggot flies specializing on different host plants (apples versus hawthorns).

Reproductive isolation, the inability of two groups to interbreed and produce fertile offspring, is essential for both allopatric and sympatric speciation. It prevents gene flow and allows independent evolutionary pathways to diverge.

Question 3: Types of Natural Selection

Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. Three main types of natural selection are:

1. Directional selection: This favors one extreme phenotype over others. Example: The evolution of long necks in giraffes, where those with longer necks had an advantage in reaching higher leaves.

2. Stabilizing selection: This favors intermediate phenotypes, reducing variation. Example: Human birth weight – babies with intermediate weights have higher survival rates.

3. Disruptive selection: This favors both extreme phenotypes, potentially leading to speciation. Example: A population of finches with different beak sizes to utilize different food sources.

Environmental factors such as food availability, climate, predators, and competition play a crucial role in shaping the direction and intensity of natural selection.

Question 4: Evidence for Evolution

The theory of evolution is supported by a wealth of evidence from various fields:

1. Fossil record: Fossils show transitional forms between different groups of organisms, demonstrating evolutionary change over time. Example: The evolution of whales from land mammals is supported by a series of fossils showing intermediate forms.

2. Comparative anatomy: Homologous structures (similar structures with different functions) in different species suggest common ancestry. Example: The forelimbs of vertebrates (humans, bats, whales). Analogous structures (different structures with similar functions) suggest convergent evolution due to similar environmental pressures. Example: Wings of insects and birds.

3. Molecular biology: Similarities in DNA, RNA, and protein sequences across species indicate common ancestry. Example: The genetic code is nearly universal across all living organisms.

4. Biogeography: The geographic distribution of species reflects their evolutionary history and the movement of continents. Example: The presence of marsupials in Australia and their absence in other continents.

Question 5: Genetic Drift

Genetic drift is a random change in allele frequencies due to chance events. It's more pronounced in smaller populations because random fluctuations have a larger impact on the gene pool. Two significant examples are:

1. Bottleneck effect: A drastic reduction in population size due to a catastrophic event (e.g., earthquake, disease) randomly eliminates alleles, altering allele frequencies in the surviving population.

2. Founder effect: A small group of individuals establishes a new population, carrying only a subset of the original population's genetic variation. This leads to different allele frequencies in the new population compared to the source population.

These effects can lead to significant changes in allele frequencies, potentially reducing genetic diversity and increasing the chance of fixation (one allele becoming the only allele present) for certain alleles. Genetic drift can be a significant evolutionary force, especially in small and isolated populations.